Drug class: Keratolytic Agents

Medically reviewed by Drugs.com on Nov 10, 2024. Written by ASHP.

Introduction

Urea, at concentrations of 10–30%, promotes hydration of keratin and mild keratolysis in dry and hyperkeratotic skin.

Uses for Urea (Topical)

Urea is used topically in the treatment of dry skin. At concentrations of 10–30%, urea promotes hydration of keratin and mild keratolysis in dry and hyperkeratotic skin. The drug increases the uptake of water by the stratum corneum, giving it a high water-binding capacity. Topically applied urea may also have an antipruritic effect. At high concentrations (e.g., 40%), urea is a protein denaturant.

Urea (Topical) Dosage and Administration

Urea is applied topically as a cream or lotion. The moisturizing effect of urea may be enhanced by applying the preparation to the skin while it is still moist after washing or bathing. Urea is applied topically to the affected area 1–3 times daily or as directed by a physician.

Cautions for Urea (Topical)

Adverse Effects

When used in appropriate dosage, topically applied urea preparations have a low order of toxicity. Transient stinging may occur, especially when urea preparations are applied to the face or broken or inflamed skin. Local irritation may also occur following topical application of urea.

Precautions and Contraindications

Topical preparations containing urea are intended for external use only. Topical urea preparations should be applied with caution to the face or broken or inflamed skin. Urea should not be used near the eyes.

Some commercially available topical formulations of urea contain sulfites that may cause allergic-type reactions, including anaphylaxis and life-threatening or less severe asthmatic episodes, in certain susceptible individuals. The overall prevalence of sulfite sensitivity in the general population is unknown but probably low; such sensitivity appears to occur more frequently in asthmatic than in nonasthmatic individuals. Topical urea preparations should be discontinued if local irritation or rash occurs during use.

Chemistry and Stability

Chemistry

Urea, the diamide of carbonic acid, occurs as colorless to white, prismatic crystals or as a white, crystalline powder. The drug is freely soluble in water and soluble in alcohol and has a cooling, saline, unpleasant taste; it is practically odorless but may gradually develop a slight ammoniacal odor on long standing. An endothermic reaction occurs on dissolution of urea; to shorten dissolution time, the diluent may be warmed in a water bath to a temperature of 60°C before mixing with urea.

Stability

Upon standing, heating, or exposure to acids or alkalies, urea is hydrolyzed to ammonia and carbon dioxide. Solutions of urea are unstable and cannot be sterilized by heat. Urea should be stored in well-closed containers.

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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